We are going somewhat "off topic" here, but I'll try and give you some pointers.
Not all web space is equal.
Many Internet Service Providers will give you a limited amount of "free" web space as part of your broadband/dial up connection deal. Such space is generally around 50 MB, and lacks many of the bells and whistles of "premium" web hosting, but is quite adequate for most personal web sites.
There are also many "free web hosting" providers. Usually this comes at the "price" of having adverts on your web pages.
Then there is "paid" hosting, where you pay an annual, or monthly fee to a web hosting company who provides you with web space for your web site.
Many of the free hosting options have limitations concerning the size of files that you can upload, and the method of uploading. Frequently the hosting company will provide a web based interface through which you can access your web space through a web browser (such as Firefox or Internet Explorer) and upload your files, create directories (folders), modify file names, and so on. While this is convenient for new users, it is the least flexible way of managing the content of your web site.
A much better way, is if your hosting provider gives you "ftp" access.
We are all familiar with "http" (even if we don't know what it means

)
Basically, http is a "protocol", a kind of language that web browsers and web servers use to communicate with each other. It allows your web browser to request which web page it wants, then the server can send the appropriate page to the browser.
"ftp" is similar, in that it is an internet protocol, but rather than it being specifically for downloading web pages from the web hosts machine (the "server" application) to the browser (the "client" application), it is designed for transferring files in either direction. "ftp" = "file transfer protocol".
In order to use ftp, you need an ftp client program. A good (and free) program for this is "Filezilla".
If your web host has ftp available, the hosting company will supply you with the necessary information that you need for your ftp client to access your web space. This will include the "ftp address", your user name and a password, and possibly a few other details. When you "connect" to your web space with an ftp client, you will (usually, but it depends on which ftp program you use) see one window with your "local" files (files on your computer - just like an explorer window), and another similar window that shows the files and folders in your allocated web space. You can then copy files from one window to the other, create directories, rename, create and delete files, very much like you would on your own computer.
For the Filezilla client:
http://filezilla-project.org/
More information about web hosting:
http://en.wikipedia.org/wiki/Web_hosting
PS. If you are intending to use paid hosting (as opposed to free web hosting), do your research - the price and quality vary tremendously and there are lots of deals that look great but can either work out far more expensive than they should, or provide a very disappointing service. After years of searching the market for a reliable web host that could offer the service that I wanted, and all the features that I wanted, I ended up setting up my own web hosting. Of course, if you get free web hosting with your internet account, then although it is usually pretty basic, the reliability is usually pretty good, and the price is right. The main limitation of this kind of hosting is that you are usually limited to using a web address that is a "subdomain" of their web site rather than your own domain name (your own "dotcom").